Drying roll



Oct. 18, 1960 G. F. MUELLER DRYING ROLL Filed Aug. 6, 1956 7 5 3 3 3 .o .u 3 n u 3 u .n 1 9 um H n. s Z o W 5 United States Patent Oli ice Patented Oct. 18, 1960 DRYING ROLL George F. Mueller, Abington, Pn., assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware l Filed Aug. 6, 1956, Ser. No. 602,112

4 Claims. (Cl. 34-` 124) 'The present invention relates to a drying roll for drying traveling sheets of exible material such as cellophane. In particular, the invention relates to a drying roll which maintains a temperature differential between the end andv central surface portions of the roll.

In the production of continuous exible sheet material such as cellophane, the general practice is to dry the wet sheets by passing them over a series of rotating hollow rolls which are internally heated by a suitable heating medium such as steam or hot water. With these rolls, the entire roll surface is maintained at substantially uniform temperature. In view of this factor, many diculties and disadvantages are encountered which tend to produce nal sheet products of inferior quality.

When using the above described rolls of uniform surface temperature, it has been found that the edge portions l of the lm or sheet are dried more rapidly than the more central portions of the film whereby the final film has a non-uniform moisture content. As a result of the faster edge drying, the edge portions of the sheet are sometimes in brittle condition in view of the fact that their moisture content is less than that of the remaining portions of the sheet. In addition, the sheet edge portions shrink more rapidly than the central portions of the `sheet whereby the final lm or sheet has curly or opping edges which tend to tear or rip at the slightest provocation; thus marring or damaging the entire sheet. Obvious difculties are encountered when using such a sheet of non-uniform strength and moisture content in wrapping machines, packaging machines, multi-color printing machines, etc.

Various drying methods and apparatus have been devised in the past in an attempt to overcome these difficulties and disadvantages mentioned above. To date, none of these methods or apparatus has proved entirely satisfactory. v For example, efforts have been made to mechanically prevent uneven shrinkage of the film during the drying operation by clamping or gripping the sheet or film at the lm edges thereby applying tension to the sheet away from the sheet center and counteracting any rapid shrinkage of the sheet vedge portions. It was found, however, that the clamps tend to tear or rip the edge portions of the sheet or lm.

It is therefore one object of my invention to provide a novel and improved drying roll for traveling sheets of flexible material which can be used to produce nal sheets which have uniform moisture content and a uniform shrinkage pattern.

Another object of my invention is to provide a novel and improved drying roll wherein a temperature dilerential is maintained during operation between the end and more central portions of the roll surface.

Still another object of my invention is to provide a novel and improved drying roll which has means for controlling the circulation of the heating medium within the drum interior to provide cool ends for the drying roll.

Other objects and advantages of my invention will become more apparent from a study of the following description and drawing wherein:

Figure 1 is a longitudinal section of my drying roll showing the inner structure of the roll;

Figure 2 is a longitudinal section of my drying roll showing an embodiment of the roll;

Figure 3 is a partial section taken along lines III-III of Figure l; and

Figure 4 is a partial section taken along lines of Figure 2.

Briey, my drying roll comprises a drum having a pair of sealed-off airtight spaced-apart compartments of substantially cylindrical shape Within the drum interior. These compartments lie in a spaced, end-to-end relationship longitudinally of the drum whereby a central cham-' ber within the drum interior is provided between the compartments. A substantially annular channel lying between the compartment outer surfaces and the inner surface of the drum extends for the length of the drum and communicates with the chamber between the compartments. Means are provided for introducing a heating medium into the central chamber between the cornpartments, and heating medium collecting means which l Figure 1, my drying roll comprises an open end drum 1 having end closures 3 and 5 which seal oli the drum ends. Within the drum 1 there is supported an inner shell 7 of substantially cylindrical shape and of somewhat smaller diameter than the drum 1. The shell 7 extends for the full length of the drum 1 and is supported in position within the drum interior by the end closuresV 3 and 5. Since the shell is of smaller diameter than that of the drum, an annular channel 8 lies between the inner surface of the drum 1 and the outer surface of shell 7 and extends the full length of the drum. As seen in the drawing, a pair of partition plates 9, 9 are positioned within and form a seal lit with the inner shell 7 to equally divide the interior of the shell 7. The partition plates 9, 9 are supported in spaced-apart end-to-end relationship whereby a central chamber 11 is provided within the shell interior. This central chamber 11 communicates with the annular channel 8 through a plurality of ports 13, 13 extending around' and through that portion of the shell 7 surrounding and lying between the partition plates 9, 9 (see Figure 3). t

Adjacent each end of the shell 7 and positioned within the shell interior are a pair of end plates 15, 15 which also lie in spaced-apart relationship and form a seal tit with the inner surface of the shell 7. The spaced-apart end plates 15, 15 define a collecting chamber 17 at each end of the shell which communicates with the annular channel 8 through a series of ports 19, 19 which extend through the end portions of the shell surrounding and lying between each pair of end plates 15, v15. The innermost end plates 15, 15 seal olf the outer ends of each compartment mentioned above to provide a pair of sealedof`t` compartments 21, 21 within the shell interior. Extending through the end closure 3 is a discharge conduit 23 which extends through the drum interior for substantially the length of the drum, including the end plates 15, 15 and the central partition plates 9, 9. The collecting chambers 17, 17 are in communication with the discharge conduit through a plurality of ports 25, 25 extending through and around those portions of the discharge conduit which pass through the collecting chambers 17, 17.

A heating medium supply conduit 27 also extend through the end closure 3 and is concentrically supported within the discharge conduit 23. The inner end of the supply conduit 27 terminates at a point adjacent the Vmiddle of the shell '7; and has a plurality of radially exis secured to the discharge conduit 23 for rotating the As seen in the drawing, the outer end of the discharge conduit 23 opens into a collecting basin 35 which leads into a recirculation system (not shown) for the heating medium. The supply conduit 27 is supported for rotation with the drum by a rotary joint assembly 37. Both the discharge conduit 23 and the supply conduit 27 for the heating medium rotate with the drum 1.

With the above arrangement, the heating medium passes throughvthe supply conduit 23 into the chamber 11 between the partition plates 9, 9, through the ports 13, 13 of the'shell 7 and into the annular channel 8 extending longitudinally ofthe drum 1. The heating medium is then divided into -two streams which pass in opposite directions toward each drum end at which point the streams pass through the ports`19, 19 of the collecting chambers 17, 17. From the collecting cham' .-rs, the medium passes into the discharge conduit 243 through the discharge conduit ports 25, 2-5. The Vvrri'edium then passes into the collecting basin 35 from whih point it is re.ir culated through the drum interior. j

As the heating medium travels outwardly through the channel 8 toward each end of the drum 1, it, of course,`

decreases in temperature since the more central surface portions of the drum absorb the heat from the medium. The end surface portions of the drum are therefore somewhat cooler than the more central surface portions of the drum.

Another embodiment of my drier roll is shown in Figure 2 of the drawing. With the arrangement shown in Figure 2, the hot point of the drum surface may be varied adjacent the center point of the drum surface by later-ally adjusting the point at which the heating medium strikes the inner periphery of the drum. Such adjustability isv desirable since dilerent types of sheet material, or even the same type of sheet material, exhibit different drying characteristics or patterns.

With this embodiment, the inner shell 7 has a plurality of elongated' slots 50, 50 extending through and around the shell adjacent the mid-point thereof instead of the ports 13, 13 of the shell of Figure 1. Supported within and forming a seal lit with the inner surface of the shell 7 is a second inner shell 52 which is substantially shorter than the shell 7. The second shell 52 lies immediately adjacent the slots 50, 50 of the shell 7 and extends for a short'Idistance beyond either side of the slots. Within the second shell 52 are positioned and secured, to form a seal lit with the inne'r surface of shell 52, a pair 'of spaced-apart partition plates 54, 54 which define a central chamber 56 therebetween. The plates 54, 54 have a convex hub portion which tits around and forms a seal t with the discharge conduit 23. A plurality of rods 58 (see Figure 4 also) extend through the drum end closure 3 and through the partition plates 54, 54 supported within the second inner shell 52. The interior end of the rods 58, 58 are threaded as at 60 and cooperate with tapped holes cut through the partition plates 54, 54. ZBy rotating the rods 58,58 simultaneously in either a clockwise or counter-clockwise direction, the inner shell .52 may be moved laterally of theshell 7 in either a back- Ward or forward motion. This action will, of course, change the position of the ports 53, 53 extending through and around that portion of the second inner shell 52 sur- :rounding and lying between the partition plates 54, 5ft 75 with respect to the elongated slots 50, 50. The stops 62, 62 at the end of each threaded section 60 of the rods 58, 58 prevent the ends of the shelly 52 from passing beyond the range of the slots 50, 50 so that the seal fit between the lirst and second shells 7 -and' 52 may be maintained. With this adjustable feature, the heating medium may be directed through the slotsj50, 50 at various points along the slot length to vary the point at which the medium rst contacts Ithe inner surface of the drum or, in other words, to adjust the hot point'of the drumsurface.

The heating medium is circulated in the same manner as described above with respect to the structure of Figure l.

While preferred embodiments of the invention have been shown and described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A drying roll comprising a drum, end closures for the drum, a cylindrical inner shell within the drum extending the length of the drum and providing an annular channel between the inner surface of the drum and the outer surface of thc shell, a pair of spaced-apart partition plates positioned within and adjacent the center of the inner shell and forming a seal tit withA the inner surface of the inner shell to separate the shell interior into two compartments and provide a central chamber between the plates, a plurality of ports extending through and around that portion of the shell lying over and between the partition plates whereby the central chamber ing medium collecting chambers integrally incorporated within the interior of each compartment, said collecting chambers each being delned by a pair of spaced-apart plates at each end of the shell which form a seal with the inner surface of the shell, means dening a plurality of ports extending through that portion of the shell lying over and between said last-mentioned spaced-apart plates whereby the collecting chambers communicate with the annular channel, a heating medium discharge conduit extending longitudinally of the drum through one of the drum end closures into and through the spaced-apart plates of the collecting chambers and the partition plates forming the central chamber, and means for rotating the drum.

2. A drying roll according to claim l wherein those portions of the discharge conduit which lie within the collecting chambers are provided with a plurality of ports whereby the collecting chambers are in communication with the discharge conduit.

3. A drying roll according to claim l wherein the means for introducing heating medium comprises a supply conduit concentrically positioned within the discharge conduit, said supply conduit terminating within said central chamber, and a plurality of radially extending nozzles extending from the supply conduit through the wall of the discharge conduit to place the supply conduit in communication with the central chamber.

4. A drying roll according to claim l wherein means is provided for moving said partition plates as a unit toward the ends of the drum whereby the .location of said central chamber may be varied;

References Cited in the tile of this patent UNITED STATES PATENTS 375,889 Oliver Jan. 3, 1888 1,657,212 Hitchcock Ian. 24, 1928 2,582,365. Westphal Jan. l5, 1952 2,300,528 Sherts Nov. 3, 1952 2,712,923 Wynne July 12, 1955 FOREIGN PATENTS 257,892 Great Britain Apr. 28, 1927 

